If you want to 3D print arbitrary shapes with an FDM printer, you often find you need supports. If you have dissolvable support material, that might not be a big issue, but if you use the same material for support as you print in, removing it can be difficult, depending on the location of the support and your slicer. At the very least, it is going to require more time and filament to print and at least some post-processing. [Slant 3D] asserts that you can always redesign the part using chamfers and fillets to avoid needing support to start with. Watch the video, below.
Of course, sometimes you just need to flip the part around. For example, the part in question — which is just an example — could just be rotated to avoid support, but that isn’t the point, of course. A fillet, however, still might need support, so you wind up having to do a double fillet to really avoid support.
The answer, according to the video, is a chamfer. The steady change in angle is easy to print, although not all designs will allow a steep chamfer. So picking the angle is the key and you might even mix both chamfers and fillets.
Creating chamfers and fillets might be easy or difficult, depending on your CAD package of choice. OpenSCAD is notoriously difficult to add these things, but you can use FreeCAD which can interoperate with OpenSCAD to make it easier. There are also a number of libraries available. Speaking of FreeCAD, we saw that tool used in another method to avoid supports: print flat and fold.